The present invention relates to a multiplex digital echo suppression system for suppressing echoes produced in the channels of the satellite communications system and the marine cable communications system without deciding the multiplexed digitally coded signals into the voice signals.
In the satellite communications system, there has been a problem that the speaker cannot clearly hear the receiver voice because the echo of the speaker's voice is included in receiver's voice. In the conventional analog echo suppression systems devised and developed for overcoming this problem, one analog echo suppressor must be provided for each channel, is large in size and consumes much energy. Therefore there arise the problems of tremendous initial cost and large installation space because one echo suppressor must be provided for each of thousands telephone channels in each earth station in the domestic satellite communications system.
There has been also devised and demonstrated a digital type echo suppression system in which the analog signal is converted into the digital signal by an analog-to-digital converter. But this system also has an inherent defect that one echo suppressor must be provided for each channel. There has been also devised and demonstrated a multiplex digital echo suppression of the type in which the complex logical operations of the digital signal are carried out in order to detect the peak value of the digital signal, but the circuit configurations are much too complex for practical purposes.